1. Field of the Invention:
The present invention relates to insulating boots for use with electrical devices mounted in electrical outlet boxes.
2. Discussion of Background:
A variety of electrical devices are installed in the walls of homes and offices. Electrical devices typically include electrical outlets, snap light switches, dimmer light switches, telephone jacks and television cable connections. These devices are mounted within outlet boxes, which are metal boxes substantially but not completely closed on five of their six sides. Outlet boxes are attached to the wall studs or other framing in such a way that the electrical devices will be flush with the wall surface when attached thereto (and a cover plate placed thereover). An outlet box may have several holes for admitting electrical wires or cables. The outlet box is grounded but one or more terminals on the device installed therein will be at an electrical potential above ground potential.
The spacing between the device and the box is small. For example, a typical commercial grade snap switch is one and one-quarter inches wide by two and one-quarter inches high. It will be placed in a box that is typically one and seven-eighths wide by three inches high. Thus, there will be five-eights inch to split between the top and the bottom of the device and three-quarters inch to split between the sides of the device, which is where the terminals are, and the sides of the box. Shorting an electrical terminal against the box is not only possible but all too easy to do.
In many cases, several such devices, especially light switches and electrical outlets, may be placed side by side in one larger outlet box. These ganged arrays of devices present a special electrical shorting problem. Because the electrical terminals are on the sides of the devices, adjacent devices can be shorted to each other when contact is made in the course of servicing or installing these devices if still receiving power, as they must be when trouble-shooting a circuit.
When two or more devices are ganged together in a single outlet box, they are often served with alternate electrical phases, which results in a higher effective voltage across the terminals of adjacent devices. For example, if the voltage available is two-phase, the adjacent terminals can have a 220 volt difference based on 110 VAC. It is not uncommon for the voltage difference between two adjacent devices to be as much as 480 VAC. This situation is a violation of the National Electrical Code, Section 380-8(b) (1990), which requires that a grouping of switches be avoided unless the voltage between adjacent switches does not exceed 300 volts, or unless the enclosures have permanently installed barriers between adjacent switches. Unfortunately, no outlet boxes are known to be commercially available that have "permanently installed barriers." Furthermore, this requirement is routinely overlooked by electrical engineering firms in specifying the electrical requirements of a home or office. The consequences of shorting 480 volts is damage to property and injury to the electrician.
Boots that protect electrical devices against moisture and vermin are known. See U.S. Pat. No. 4,576,428 issued to DeLuca for an example of such a device. Wire wrappings to isolate wires electrically are also known, as illustrated by the device disclosed in U.S. Pat. No. 4,742,123 issued to Haub, Jr. Insulators for adjacent terminals are also known. See U.S. Pat. No. 2,636,065, issued to Fiske.
However, there remains a need for an easily implementable solution to the problem of shorting the electrical terminals of electrical devices against the sides of the outlet box in which it is mounted or against an adjacent device.